Scotland’s police union boss has been found guilty of posting “inappropriate and offensive” online comments about a female ex-police chief.

Constable Calum Steele branded former assistant chief constable Angela Wilson “one of the most incompetent imbeciles ever to have held rank in the police service”, “useless” and a “buffoon”.

The Scottish Police Federation (SPF) general secretary also alleged that a corruption inquiry “extended” to her – prompting Wilson to complain to Police Scotland.

Upholding the complaint, Chief Inspector Jacqui Campbell, of the Professional Standards Department (PSD), ruled the comments were “inappropriate and offensive” and that Wilson was “never investigated for corruption”.

Steele claimed to be off duty when he launched the Twitter tirade on May 3 but the PSD probe discovered that he was working.

Campbell said: “The record revealed Constable Steele’s duty for that date was 0900 to 1700 hours, therefore, at the time the tweets were posted he was on duty.”

Campbell has issued Wilson a “sincere apology for the undoubted upset Constable Steele’s actions have caused”.

But Steele – who heads the federation representing 98 per cent of Police Scotland officers – “makes no apology” and refuses to delete the messages.

Campbell said: “We have asked Constable Steele to remove the relevant tweets from his Twitter account. Unfortunately, it is his own personal Twitter account and, as such, we are unable to order him to remove or delete them.”

Despite Steele’s messages being from a personal account, Campbell found “they are directly related to his role as a police officer and particularly his role as general secretary” of the SPF.

The federation boss attacked Wilson after she said interim Chief Constable Iain Livingstone should not get the job permanently due to a previous sexual attack allegation.

Our story on police Twitter row (Image: Sunday Mail)

Livingstone was cleared of assaulting a female junior officer at a police college in 2000 but was demoted from superintendent to constable, which was later reversed on appeal.

Steele accused Wilson of having an “axe to grind” along with ex-chief constable Phil Gormley and his wife Claire. Wilson told the PSD that when she had previous dealings with Steele, he had been disrespectful and misogynistic. The former senior officer, now chair of the Women’s Rape and Sexual Abuse Centre in Dundee, declined to comment.

But a source said: “Calling someone nasty names on Twitter is bad enough but making a false allegation of corruption is outrageous.

“Any police officer, especially a full-time federation official, ought to know better. It was vitally important for Angela that he was held to account and that his claims were proven to be completely false.”

Steele, who spoke to PSD officers through a lawyer, now faces a further hearing which may result in disciplinary action. His lawyer quoted a dictionary definition of “imbeciles” as meaning “a fool” and that it was “a fair and honest comment that represents Constable Steele’s honestly-held belief”.

Chief Superintendent Mark Hargreaves, head of the Professional Standards Department, said: “The investigation into this complaint has concluded and as this is an internal matter it would be inappropriate to comment further.”